Emily Dickinson Lexicon

EX-ERT', v.t. [egzert'; L. exero, for exsero; ex and sero, to throw, to thrust, for this is the radical sense of sero.]

1. Literally, to thrust forth; to emit; to push out. Dryden. Before the gems exert / Their feeble heads. Philips. [An unusual application.]
2. To bring out; to cause to come forth; to produce. But more generally,
3. To put or thrust forth, as strength, force, or ability; to strain; to put in action; to bring into active operation; as, to exert the strength of the body or limbs; to exert efforts; to exert powers or faculties; to exert the mind.
4. To put forth; to do or perform. When the will has exerted an act of command on any faculty of the soul. South. To exert one's self, is to use efforts; to strive.